[Dovecot] Mount options and NFS: just checking...
Greetings -
I'm now in the last couple of weeks before going live with Dovecot
(v1.0.3) on our revamped IMAP service. I'd like to double-check
about the best mount options to use; could someone advise, please?
I have three separate directory trees for the message store, the
control files and the index files. These are arranged as follows:
Message Store Mounted over NFS from a NetApp filer; filestore quotas are ENABLED.
Control Files
Mounted over NFS from the NetApp filer; filestore quotas are
DISABLED.
Index Files Mounted on local disk; filestore quotas are DISABLED.
We will have a pair of Solaris 10 servers on which Dovecot 1.0.3 is
running. Users are normally directed to their "preferred" server
but, if it is unavailable, will go via the other server.
Q1. Am I right in thinking that for the Message Store and Control Files I should NFS-mount both of them with the "actimeo=0"?
(Or would "noac" be better, which also turns off client write- caching as well as the attribute cache?)
Q2. Should I NFS-mount either or both of the Message Store and
Control Files
with the "noxattr" option to turn off extended attributes?
Q3. Which of the filestores should I mount with the "noatime" option?
(I understand that for the filer-based NFS mounts this can be
done on the
filer, as the option isn't available with "mount" for NFS-monted
filestores.)
Q4. Any other options to use/miss out?
Currently my understanding from the list and the NFS page at the Wiki
is:
A1. Use "actimeo=0" for both Message Store and Control Files. No idea about the need for/impact of using "noac".
A2. No idea.
A3. Safe to use "noatime" for all three filestores.
(I understand Dovecot will use utime() when needed on such
filestores,
but am not sure if it will work on the NFS-mounted filestores
from the
filer if access times are turned off at the filer end.)
Any thoughts, please?
Cheers, Mike B-)
-- The Computing Service, University of York, Heslington, York Yo10 5DD, UK Tel:+44-1904-433811 FAX:+44-1904-433740
- Unsolicited commercial e-mail is NOT welcome at this e-mail address. *
On Wed, 2007-08-01 at 12:54 +0100, Mike Brudenell wrote:
We will have a pair of Solaris 10 servers on which Dovecot 1.0.3 is
running. Users are normally directed to their "preferred" server
but, if it is unavailable, will go via the other server.Q1. Am I right in thinking that for the Message Store and Control Files I should NFS-mount both of them with the "actimeo=0"?
Since files in message store don't change, actimeo=0 isn't really needed, although if other servers are adding mails to maildirs then it does make noticing new mails faster.
For control files actimeo=0 is needed for now.
(Or would "noac" be better, which also turns off client write-caching as well as the attribute cache?)
If you're not using fsync_disable then write caching shouldn't be a problem.
Q2. Should I NFS-mount either or both of the Message Store and
Control Files with the "noxattr" option to turn off extended attributes?
No idea. Dovecot doesn't use them, so I don't think it breaks anything, but does it give any benefits?
Q3. Which of the filestores should I mount with the "noatime" option? A3. Safe to use "noatime" for all three filestores. (I understand Dovecot will use utime() when needed on such
filestores, but am not sure if it will work on the NFS-mounted filestores
from the filer if access times are turned off at the filer end.)
If your kernel caches atime updates locally, then maybe you shouldn't use noatime for message store until v1.1. It doesn't cause real problems, but Dovecot wastes time looking for old files in tmp/ directories all the time.
Hi, Timo -
On 1 Aug 2007, at 13:14, Timo Sirainen wrote:
Q3. Which of the filestores should I mount with the "noatime"
option? A3. Safe to use "noatime" for all three filestores. (I understand Dovecot will use utime() when needed on such filestores, but am not sure if it will work on the NFS-mounted filestores from the filer if access times are turned off at the filer end.)If your kernel caches atime updates locally, then maybe you shouldn't use noatime for message store until v1.1. It doesn't cause real problems, but Dovecot wastes time looking for old files in tmp/ directories all the time.
Many thanks! I think I'm nearly there now: could you just clarify on
the items flagged with (??) below?
In case it makes a difference, messages will generally be delivered
by a user's preferred IMAP server, but by Exim rather than Dovecot's
"deliver".
"actimeo=0" option
NFS-mounted Message Store: NOT needed, but if used can help spot
new messages
more quickly
NFS-mounted Control Files: REQUIRED for now
Local Index Files: Not applicable
"noatime" option
NFS-mounted Message Store: Probably OK to use, but safer not to
until v1.1
NFS-mounted Control Files: Can be used safely(??) (Or as above??)
Local Index Files: Can be used safely(??)
With many thanks, Mike B-)
-- The Computing Service, University of York, Heslington, York Yo10 5DD, UK Tel:+44-1904-433811 FAX:+44-1904-433740
- Unsolicited commercial e-mail is NOT welcome at this e-mail address. *
On Wed, 2007-08-01 at 14:19 +0100, Mike Brudenell wrote:
In case it makes a difference, messages will generally be delivered
by a user's preferred IMAP server, but by Exim rather than Dovecot's
"deliver"."actimeo=0" option NFS-mounted Message Store: NOT needed, but if used can help spot
new messages more quickly
If only preferred server delivers mails then the messages are noticed soon anyway.
"noatime" option NFS-mounted Message Store: Probably OK to use, but safer not to
until v1.1 NFS-mounted Control Files: Can be used safely(??) (Or as above??) Local Index Files: Can be used safely(??)
Safe. Only maildir tmp/ cleanup checks atimes.
participants (2)
-
Mike Brudenell
-
Timo Sirainen